Figure 1

Resistance of the ΔarcA and ΔarcB mutant of E. coli to H ₂ O ₂ . (A and B) Growth and survival of wild type E. coli (diamond), ΔarcA mutant E. coli (square), ΔarcA mutant E. coli transformed with plasmid pRB3-273C (triangle) and ΔarcA mutant E. coli transformed with plasmid pRB3-arcA (cross) in LB broth with 1.5 mM H₂O₂ (A) or LB broth alone (B). (C and D) Growth and survival of wild type E. coli (diamond), ΔarcB mutant E. coli (square) and ΔarcB revertant mutant E. coli (cross) in LB broth with 1.5 mM H₂O₂ (C) or LB broth alone (D). Bacterial concentration was determined by plating and plotted against the indicated incubation time period. At least three experiments were performed, and results from a representative experiment performed in triplicates are shown. Error bars indicate standard deviation and sometimes fall within the data label.